1. Technical Field
The present disclosure relates to a photoelectric conversion element.
2. Description of the Related Art
In recent years, solar cells are growing in importance as alternative energy to fossil fuels and measures against global warming. Existing solar cells, represented by silicone solar cells, are too expensive to be in widespread use.
Low-cost solar cell technologies are under research and development. For example, Graetzel et al. (from Swiss Federal Institute of Technology in Lausanne) have presented a dye-sensitized solar cell. This solar cell consists of a transparent conductive glass substrate, a porous metal oxide semiconductor provided on the substrate, a sensitizing dye adsorbed to the surface of the semiconductor, an electrolyte having a redox pair, and an opposite electrode. This solar cell has been notably improved in photoelectric conversion efficiency because of the increased surface area of the metal oxide semiconductor electrode, such as titanium oxide, owing to its porous configuration, and monomolecular adsorption of a ruthenium complex as the sensitizing dye.
However, the ruthenium complex, used as the sensitizing dye, is a rare metal having resource constraint issue. For this reason, organic sensitizing dyes free from resource constraint issue are demanded.
Various dyes have been proposed as sensitizing dyes for use in photoelectric conversion elements but none of them has sufficient characteristics.